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Fencer Vulns
high 8.1

CVE-2026-42602 json

azureauthextension Authenticate method does not validate bearer tokens, allowing auth bypass via replay

published 2026-05-06 6 mo ago modified 2026-10-26 14 d ago also GHSA-pjv4-3c63-699f , GO-2026-5544 , EUVD-2026-30160

cvss
8.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 12%
public exploits
0
none known

Summary

azureauthextension is the Azure Authenticator Extension. From 0.124.0 to 0.150.0, a server-side authentication bypass in azureauthextension allows any party who holds a single valid Azure access token for any scope the collector's configured identity can mint for to authenticate to any OpenTelemetry receiver that uses auth: azure_auth. The extension's Authenticate method does not validate incoming bearer tokens as JWTs. Instead, it calls its own configured credential to obtain an access token and compares the client's token to the result with string equality — and the scope for that server-side token request is taken from the client-supplied Host header. As a result, a token minted for any Azure resource the service principal has ever been issued a token for (ARM, Graph, Key Vault, Storage, etc.) will authenticate to the collector if the attacker picks a matching Host. Tokens are replayable for the full issued lifetime (commonly several hours for managed identity tokens).

Patch / fix

  • go github.com/open-telemetry/opentelemetry-collector-contrib/extension/azureauthextension 0.151.0
  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1

opensuse advisories openSUSE-SU-2026:21483-1

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
5 mo ago

Exploit prediction

0.22% chance of exploitation in the next 30 days, higher than 12% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/open-telemetry/opentelemetry-collector-contrib/security/advisories/GHSA-pjv4-3c63-699f referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 8.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
GitHub 3.1 8.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

Affected packages

ecosystem package affected fixed in
go github.com/open-telemetry/opentelemetry-collector-contrib/extension/azureauthextension
>=0.124.0, <=0.150.0
>=0.124.0, <0.151.0
0.151.0

Affected products

  • open-telemetry opentelemetry-collector-contrib

Classification

Weakness
  • CWE-208 Observable Timing Discrepancy
  • CWE-287 Improper Authentication
  • CWE-290 Authentication Bypass by Spoofing
  • CWE-294 Authentication Bypass by Capture-replay
  • CWE-347 Improper Verification of Cryptographic Signature

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.